In some cases, an autoregulation status of a patient may be monitored, e.g., during a medical procedure. Cerebral autoregulation (CA) is a physiological process that attempts to maintain an optimal cerebral blood flow over a wide range of blood pressure changes to supply appropriate levels of oxygen and nutrients to the brain. Complex myogenic, neurogenic, and metabolic mechanisms may be involved in CA.
During autoregulation, cerebral arterioles dilate or constrict to maintain optimal blood flow. For example, as blood pressure decreases, cerebral arterioles dilate in an attempt to maintain blood flow. As blood pressure increases, cerebral arterioles constrict to similarly maintain the blood flow that, if left unrestricted, could cause injury to the brain. Intact cerebral autoregulation function occurs over a range of blood pressures defined between a lower limit of autoregulation (LLA) and an upper limit of autoregulation (ULA). If the patient's autoregulation process is not functioning properly, then the patient may experience inappropriate cerebral blood flow, which may have an adverse effect on the patient's health. For example, a drop in cerebral blood flow may cause ischemia. As another example, an increase in cerebral blood flow may cause hyperemia, which may result in swelling of the brain or edema. Autoregulation dysfunction may result from a number of causes including, stroke, traumatic brain injury, brain lesions, brain asphyxia, or infections of the central nervous system.